This study investigated time-based prospective memory (PM) performance in 76 younger and 76 older adults with a time-monitoring task in which participants were required to press a designated key every 5 minutes while watching a movie. Participants were assigned to two conditions, free and fixed monitoring. In free monitoring participants could check a clock when they wanted, but in fixed monitoring they were restricted a maximum of six times every 5 minutes. We also investigated the involvement of time perception, inhibition, and updating in time-based PM performance. We hypothesised that participants with inefficiencies in those three cognitive functions would have less strategic monitoring behaviour and would also be less accurate at the target time. In the free-monitoring condition older adults checked the clock more frequently than younger participants, but presented with a similar pattern of monitoring behaviour and increased their frequency of clock checking closer to the target time. In the fixed-monitoring condition younger participants checked the clock more frequently than older adults and showed a strategic pattern of monitoring. Older adults did not show strategic use of clock checking and their monitoring function remained unchanged. Differences in PM accuracy and monitoring behaviour are discussed according to different involvement of cognitive abilities.

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One of the most widely used tasks for investigating psychological time, time reproduction, requires from participants the reproduction of the duration of a previously presented stimulus. Although prior studies have investigated the effects of different cognitive processes on time reproduction performance, no studies have looked into the effects of different reproduction methods on these performances. In the present study, participants were randomly assigned to one of three reproduction methods, which included (a) just pressing at the end of the interval, (b) pressing to start and stop the interval, and (c) maintaining continuous pressing during the interval. The study revealed that the three reproduction methods were not equivalent, with the method involving keypresses to start and stop the reproduction showing the highest accuracy, and the method of continuous press generating less variability.

Prospective memory (PM) is the ability to remember to perform a future action at a specified later time, which is investigated through the use of event-based and time-based tasks. Prior investigations have found that PM is impaired following traumatic brain injury (TBI). However, there is limited information regarding the cognitive functions that mediate TBI and PM performance. Thus, this study investigated time-based PM in TBI patients, and the relationship among time-based PM, time perception, and executive functions. To accomplish this objective, 18 severe TBI patients and 18 healthy matched controls performed a time-based PM task, a time reproduction task, and two executive functions (Stroop and n-back) tasks. While both groups increased their monitoring frequency close to the target time, TBI patients monitored more and were less accurate than healthy controls at the target time confirming the time-based PM dysfunction in these patients. Importantly, executive functions, particularly inhibition and updating abilities, were strongly related to time-based PM performance; both time perception and executive functions are involved in time-based prospective memory in controls, whereas, only executive functions appear to be involved in TBI time-based prospective memory performance.

Prospective memory (PM) refers to memory for future intentions and is critically linked to independent living. Previous laboratory research has shown that people who have sustained a traumatic brain injury (TBI) have difficulties with PM, but few of these have used measures of PM that closely represent the types of PM activities that occur in everyday life. One measure that incorporates more ecologically valid tasks, and which also allows systematic investigation of different PM task parameters (regular, irregular, and event and time based), is Virtual Week. Consequently, in the present study, Virtual Week was administered to participants with TBI (n = 18) and demographically matched controls (n = 18). Consistent with considerable prior literature, the results indicated that people with TBI had significant difficulties executing PM tasks, with these deficits more pronounced for time-based than for event-based tasks. These data point to there being a relatively global PM deficit in people with TBI. Of particular interest was the finding that the magnitude of TBI impairment was consistent across regular and irregular tasks. Because the key distinction between these tasks is that they place low and high demands on retrospective memory, respectively, these data suggest that failures of retrospective memory are not the major cause of TBI-related impairment in PM. The implications of these results for the assessment and rehabilitation of PM impairment in people with TBI are discussed.

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